Recently, magnetic transfer methods and nanoimprinting methods that efficiently transfer two dimensional and three dimensional patterns have been developed. Magnetic transfer is a transfer technique which is performed during the production of magnetic recording media. In magnetic transfer, a magnetic transfer master disk having a fine magnetic pattern on the surface thereof is placed in close contact with a slave medium (also referred to as a transfer target medium). A transfer magnetic field is applied in this state, and information corresponding to the magnetic pattern (servo signals, for example) is transferred onto the slave medium. Meanwhile, nanoimprinting is a transfer technique which is performed during the production of DTM (Discrete Track Media) and BPM (Bit Patterned Media). In nanoimprinting, a nanoimprinting master carrier having a fine pattern of protrusions and recesses is pressed against thermoplastic resin, photocuring resin, or the like, to transfer the pattern of protrusions and recesses onto the resin. According to these techniques, master molds (including the aforementioned master disk and the aforementioned master carrier) such as those described above can transfer two dimensional or three dimensional patterns at once by being pressed against slave media, enabling nano level fine patterns to be formed easily and at low cost.
An example of a master disk which is commonly utilized in the magnetic transfer method is that disclosed in Japanese Patent No. 4151077. This master disk has a pattern of protrusions and recesses corresponding to information to be transferred on the surface thereof, and a magnetic layer coated on the surface of the pattern of protrusions and recesses. Such a master disk is generally produced by: an electroforming step that laminates a metal plate constituted by an electroformed layer onto an original plate having information to be transferred as a pattern of protrusions and to recesses formed thereon; a separating step that separates the metal plate from the original plate; a cutting step that punches out the separated metal plate to a predetermined size and shape; and a coating step that coats a magnetic layer onto the surface of the pattern of protrusions and recesses.
However, in conventional master molds which are produced by the steps described above, there is a problem that local deformations that occur during punching in the aforementioned cutting step cause warping and distortions. If the flatness of the master mold is low due to the warping and distortions, a favorable close contact state cannot be realized between the master mold and slave media. As a result, a problem that highly precise pattern transfer cannot be performed due to defects in the close contact properties will arise.
For example, in the case that the flatness of a master disk is low, protrusions that cannot contact a slave medium appropriately will be present when the master disk is pressed against the slave medium, and a problem that the magnetic pattern cannot be correctly transferred will occur. Meanwhile, in the case that the flatness of a master carrier is low, a problem that the thickness of residual film which is formed at the bottoms of the recesses of a resist layer of a slave medium will become non uniform when the master carrier is pressed against the slave medium will arise. Accordingly, the flatness of master molds is extremely important in order to precisely perform pattern transfer in the aforementioned methods for performing transfer at once.
As means for solving this problem, cushioning materials are provided at the rear surface of master molds, close contact pressure is increased, and air within close contact surfaces between master molds and slave media are removed by vacuum suction, to improve the close contact properties of master molds with slave media.